Summary/Abstract Metabolomics profiling of blood can detect subtle changes in metabolism that may presage the later development of type 2 diabetes (T2D). This can both reveal early steps in the pathway to T2D, and also provide a novel tool to identify high risk individuals. Hispanics/Latinos, the largest and fastest growing US minority population, have a 66% higher prevalence of diabetes compared to non-Hispanic whites. US Hispanics/Latinos are diverse in biological and sociocultural characteristics, and thus may have distinct diet, lifestyle and gut microbiota patterns which likely influence metabolites implicated in T2D. The Main Goal of this project is to identify metabolomics signatures for T2D risk and examine how diet, lifestyle and gut microbiota influence metabolomics profiles associated with T2D. In particular, we propose to perform high-throughput metabolomics profiling (>400 known and hundreds of unknown metabolites) of plasma from 1000 pairs of T2D incident cases and matched controls in the Hispanic Community Health Study of Latinos (SOL) to identify novel metabolomics signatures associated with incident T2D in US Hispanics/Latinos. In the SOL, we will leverage existing extensive data on laboratory measures (e.g. fasting glucose and insulin, HbA1c, and 2-hr post oral glucose tolerance test) and objectively measured behaviors (e.g., accelerometry, biomarker- measured dietary factors) relevant to T2D. Utilizing gut microbiome data from an ongoing gut microbiome project in the SOL, we will characterize gut microbial composition and functional features associated with plasma metabolomics profiles implicated in T2D and examine the role of diet in modulating gut microbiota- related metabolites. Metabolomics profiles implicated in T2D will be further examined in non-Hispanic cohorts by including 1,500 pairs of T2D incident cases and matched controls from the Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS), two ongoing prospective cohort studies with the identical metabolomics profiling platform, gut microbiome data and objectively measured diet and lifestyle factors. The inclusion of both Hispanic and non-Hispanic cohorts may offer unique insights into the role of diet/lifestyle, gut microbiota, and metabolic pathways in the development of T2D. The findings may have great potential to identify novel targets for T2D prevention and intervention.